agent/doc/cireplay.html

Tue, 08 Aug 2017 15:57:29 +0800

author
aoqi
date
Tue, 08 Aug 2017 15:57:29 +0800
changeset 6876
710a3c8b516e
parent 5029
7b23cb975cf2
parent 0
f90c822e73f8
permissions
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merge

     1 <html>
     2 <head>
     3 <title>
     4 Replay
     5 </title>
     6 </head>
     7 <body>
     9 <h1>Compiler replay</h1>
    10 <p>
    11 The compiler replay is a function to repeat the compiling process from a crashed java process in compiled method<br>
    12 This function only exists in debug version of VM
    13 </p>
    14 <h2>Usage</h2>
    15 <pre>
    16 First, use SA to attach to the core file, if succeeded, do
    17        hsdb&gt; dumpreplaydata &lt;address&gt; | -a | &lt;thread_id&gt; [&gt; replay.txt]
    18        create file replay.txt, address is address of Method, or nmethod(CodeBlob)
    19        hsdb&gt; buildreplayjars [all | boot | app]
    20        create files:
    21          all:
    22            app.jar, boot.jar
    23          boot:
    24            boot.jar
    25          app:
    26            app.jar
    27        exit SA now.
    28 Second, use the obtained replay text file, replay.txt and jar files, app.jar and boot.jar, using debug version of java
    29        java -Xbootclasspath/p:boot.jar -cp app.jar -XX:ReplayDataFile=&lt;datafile&gt; -XX:+ReplayCompiles ....
    30        This will replay the compiling process.
    32        With ReplayCompiles, the replay will recompile all the methods in app.jar, and in boot.jar to emulate the process in java app.
    34 notes:
    35        1) Most time, we don't need the boot.jar which is the classes loaded from JDK. It will be only modified when an agent(JVMDI) is running and modifies the classes.
    36        2) If encounter error as "&lt;flag&gt;" not found, that means the SA is using a VMStructs which is different from the one with corefile. In this case, SA has a utility tool vmstructsdump which is located at agent/src/os/&lt;os&gt;/proc/&lt;os_platform&gt;
    38        Use this tool to dump VM type library:
    39        vmstructsdump libjvm.so &gt; &lt;type_name&gt;.db
    41        set env SA_TYPEDB=&lt;type_name&gt;.db (refer different shell for set envs)

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